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Sep 07, 2018
British Journal of Clinical Psychology (2003), 42, 1111312003 The British Psychological Society
The Depression Anxiety Stress Scales (DASS):Normative data and latent structure in a largenon-clinical sample
John R. Crawford* and Julie D. HenryDepartment of Psychology, Kings College, University of Aberdeen, UK
Objectives. To provide UK normative data for the Depression Anxiety and StressScale (DASS) and test its convergent, discriminant and construct validity.
Design. Cross-sectional, correlational and confirmatory factor analysis (CFA).
Methods. The DASS was administered to a non-clinical sample, broadly representa-tive of the general adult UK population (N = 1,771) in terms of demographic variables.Competing models of the latent structure of the DASS were derived from theoreticaland empirical sources and evaluated using confirmatory factor analysis. Correlationalanalysis was used to determine the influence of demographic variables on DASS scores.The convergent and discriminant validity of the measure was examined throughcorrelating the measure with two other measures of depression and anxiety (theHADS and the sAD), and a measure of positive and negative affectivity (the PANAS).
Results. The best fitting model (CFI = .93) of the latent structure of the DASSconsisted of three correlated factors corresponding to the depression, anxiety andstress scales with correlated error permitted between items comprising the DASSsubscales. Demographic variables had only very modest influences on DASS scores.The reliability of the DASS was excellent, and the measure possessed adequateconvergent and discriminant validity
Conclusions. The DASS is a reliable and valid measure of the constructs it wasintended to assess. The utility of this measure for UK clinicians is enhanced by theprovision of large sample normative data.
The Depression Anxiety Stress Scale (DASS) is a 42-item self-report measure of anxiety,depression and stress developed by Lovibond and Lovibond (1995) which isincreasingly used in diverse settings. Its popularity is partly attributable to the fact
*Requests for reprints should be addressed to John R. Crawford, Department of Psychology, Kings College, University ofAberdeen AB24 3HN, UK (e-mail: [email protected]).
that, unlike many other self-report scales, the DASS is in the public domain (i.e. themeasure can be used without incurring any charge). The DASS was originally intendedto consist of only two subscalesone measuring anxiety, the other depressioneachcomposed of items that were purportedly unique to either construct. Ambiguous items(i.e. items non-specifically related to depression and anxiety) were not included in themeasure but were regarded as controls. This strategy was adopted because the authorsoriginal intention was to develop measures that would maximally discriminate betweendepression and anxiety. However, during scale development it was revealed that thecontrol items tended to form a third group, of items characterized by chronic non-specific arousal. More items were added to this group and the third scale, the stressscale, emerged. Lovibond and Lovibond maintain that, although this scale is related tothe constructs of depression and anxiety, it nevertheless represents a coherent measurein its own right.
Whilst Lovibond and Lovibonds (1995) attempt to develop a measure that maximallydiscriminates between the constructs of depression and anxiety is not unique (Beck,Epstein, Brown, & Steer, 1988; Costello & Comrey, 1967), the strategy adopted for scaleconstruction is. Conventionally, items are derived from pre-existing anxiety anddepression scales, with factor analyses of clinical data used to identify those whichmeasure different constructs. By contrast, Lovibond and Lovibond employedpredominantly non-clinical samples for scale development on the basis that depressionand anxiety represent dimensional, not categorical, constructs. Moreover, coresymptoms of anxiety and depression which were unique to one but not both of thedisorders were identified from the outset, and not on an a posteriori basis. Thus,unconventionally, the initial items selected were retained, with new items compatiblewith the emerging factor definitions successively added.
Preliminary evidence has been presented, which suggests that the DASS does possessadequate convergent and discriminant validity (Lovibond & Lovibond, 1995). A largestudent sample (N = 717) was administered the Beck Depression Inventory (BDI; Beck,Ward, Mendelsohn, Mock, & Erbaugh, 1961), the Beck Anxiety Inventory (BAI; Beck etal., 1988) and the DASS. The BAI and DASS anxiety scale were highly correlated(r = .81), as were the BDI and DASS depression scale (r = .74). However, between-construct correlations were substantially lower (r = .54 for DASS depression and BAI;r = .58 for DASS anxiety and BDI). Moreover, Antony, Bieling, Cox, Enns, and Swinson(1998) found a similar pattern of correlations in a clinical sample.
To assess the DASSs psychometric properties, Lovibond and Lovibond (1995)administered the measure to a large non-clinical sample (N = 2,914). It was found thatreliability, assessed using Cronbachs alpha, was acceptable for the depression, anxietyand stress scales (.91, .84 and .90, respectively). These values are similar to thoseobtained from clinical populations (Antony et al., 1998; Brown, Chorpita, Korotitsch, &Barlow, 1997).
At present, interpretation of the DASS is based primarily on the use of cut-off scores.Lovibond and Lovibond (1995) presented severity ratings from normal to extremelysevere on the basis of percentile scores, with 078 classified as normal, 7887 asmild, 8795 as moderate, 9598 as severe, and 98100 as extremely severe.However, these original norms were based predominantly on students. This means thatthe generalizability of their results to the normal population is uncertain. Moreover,although 1,307 of the participants in this study were non-students, no information waspresented regarding whether they were broadly representative of the general
112 John Crawford and Julie D. Henry
population; all that was stated was that they were white and blue collar workers(Lovibond & Lovibond, 1995, p. 9).
Relatedly, the influence of demographic characteristics on DASS scores has gonelargely uninvestigated. In development of the DASS, this analysis was restricted togender and age. Although the test authors did not state explicitly whether age and/orgender yielded a significant effect, . . . there was a trend towards higher scores in theyoungest and oldest age brackets (Lovibond & Lovibond, 1995, p. 28). However,Andrew, Baker, Kneebone, and Knight (2000) found that in a sample of elderlycommunity volunteers (N = 53), scores on all three DASS subscales were almost halfthose reported by Lovibond and Lovibond. It is possible that this discrepancy isattributable to idiosyncrasies in one or both of these samples or the influence ofpotential mediating factors such as years of education or occupation. Yet no study todate has assessed the influence of either of these latter variables. The relationshipsbetween demographic variables and DASS scores in the general population are ofinterest in their own right, but investigation of these relationships would also serve thevery practical purpose of identifying whether normative data should be stratified.
If the use of the DASS in research and clinical practice is to be optimal, then it is alsonecessary to delineate the underlying structure of the instrument. This is particularlyimportant given that Lovibond and Lovibond (1995) found through empirical analysesthat, in both clinical and non-clinical samples, symptoms conventionally regarded ascore to the syndrome of depression (American Psychiatric Association, 1994) wereactually extremely weak markers of this construct. Specifically, items pertaining tochanges in appetite, sleep disturbance, guilt, tiredness, concentration loss, indecision,agitation, loss of libido, diurnal variation in mood, restlessness, irritability and cryingwere excluded from the measure.
Moreover, the legitimacy of the stress scale as an independent measure must beassessed. In an influential series of papers, Clark and Watson (Clark & Watson, 1991a,1991b; Watson, Clark, & Tellegen, 1988) have argued that anxiety and depression havean important shared component which they call negative affectivity (NA). NA is adispositional dimension, with high NA reflecting the experience of subjective distressand unpleasurable engagement, manifested in a variety of emotional states such as guilt,anger and nervousness, and low NA represented by an absence of these feelings(Watson & Clark, 1984). Studies have supported the existence of a dominant NAdimension (Watson & Clark, 1984; Watson & Tellegen, 1985) and provide evidence thatit is highly related to the symptoms of both anxiety and depression (Brown et al., 1997;Watson, Clark, Weber et al., 1995; Watson, Weber et al., 1995). Thus, there are strongtheoretical grounds for suggesting that the stress scale is simply a measure of NA,particularly given that this scale actually originated from items believed to relate to bothdimensions.
To date, four studies have directly tested the construct validity of the DASS (Antonyet al., 1998; Brown et al., 1997; Clara, Cox, & Enns, 2001; Lovibond & Lovibond, 1995).Lovibond and Lovibond (1995) conducted a principal-components analysis in a studentsample (N = 717) which revealed that the first three factors accounted for a highproportion of the variance. Furthermore, all items loaded on their designated factorexcept for anxiety item 30 (I feared that I would be thrown by some trivial butunfamiliar task) which loaded on the stress factor. In the same sam